1. Field of the Invention
The invention relates to determining network conditions. More particularly, the invention provides a system and a method for determining a transmission latency and a maximum transmission bandwidth for a network connection between a server computer and a client computer.
2. Description of the Related Technology
Today, more than ever, people transmit and receive data objects, including video, text, graphic and other data, over a network. People now expect and demand that the data objects be transmitted quickly and without errors. FIG. 1 illustrates a typical data object distribution system for distributing data objects 107.
The data object 107, located on the server computer 110, is made available for further distribution over a network 100, such as the Internet, to one or more client computers 112. The client computer 112 generally requests the data object 107, begins receiving portions of it, and possibly begins rendering the data object 107 for presentation to an end user. As part of the transmission process, the server computer 110 typically breaks the data object 107 into a sequence of packets by a process called “packetization.” After packetization, the server computer 110 sends in succession each of the packets to the client computer 112.
During presentation, the server computer 110 can transmit the data object 107 at one of a variety of transmission rates. For example, the server computer 110 may initiate transmission of the data object to the client computer 112 at 20 kilobits per second (kbps). However, due to sources of interference such as, for example, noise or network congestion, or other problems, the client computer 112 may not receive the packets at a rate of 20 kbps. Thus, the actual available transmission capacity may not support a 20 kbps rate. Alternatively, transmission capacity may increase rather than decrease—even during the transmission of the data object 107. Without the ability to quickly detect changes in network conditions, the degree of change, or both, the transmission rate cannot be optimized, or even confidently improved.
Therefore, there is a need for a system that can detect network conditions. The system should be able to detect changes in latency in the transmission of packets, estimate the maximum transmission bandwidth for a network or both. The transmission latency and the maximum transmission bandwidth could advantageously be used by standard network systems, such as a transmission rate control device, to determine an optimal transmission rate for the data objects.